test-drb

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101090 discussions

by Philip.Belben＠PowerTech.co.uk

[Earth Leakage Circuit Breakers] > I am not sure what the UK IEE regulations state about them (Philip?), but > they are not that common in domestic installations. I would always use > one on a socket for something like a lawnmower or other outdoor device. The IEE regulations require that any socket likely to be used for equipment operated out of doors be protected by a residual current circuit breaker with an instantaneous tripping current of not more than 30mA. > 1) A lot of classic computers - particularly minicomputers - have proper > mains filtering. The earth leakage current of the mains filter, when > operating correctly, is enough to trip most RCDs. Useful, that. Think of it as a protection grading problem. But here you have to choose the protection settings upstream to grade with the equipment downstream. I haven't heard of such filters drawing 30mA, though. > 2) They are not a substitute for an isolating transformer. If you want to > make measurements on the primary side of an SMPSU with an earthed 'scope > then you need an isolating transformer. Put the PSU on a RCD and said RCD > will trip (correctly) as soon as you connect the earth lead of the probe. > As doing things like that is the main reason why I'd be working on a live > machine, I'd rather have an isolating transformer. And of course an RCD > won't protect you if you manage to connect yourself across the output of > the isolating transformer. True. Any protective device is useful in a specific situation, and protects against specific faults. Anything can be used where it's inappropriate. But that doesn't make it per se a bad thing. > 3) They are only of use if you touch the mains side of a supply. They are > no use at all if you manage to get connected across the output of an See above. > isolated HV supply. But IMHO having a safety device in line makes you > careless. You may not realise it, but you will depend on the RCD to save > you if you make a mistake. And then you make a mistake where it can't help. I disagree. I once said, joking, "I used to recommend steel toe-caps when moving large computers, but now I generally prefer bare feet - so you make damned well sure you don't drop it!" My view is: A protective device - any protective device - is there to get you out of trouble, not to get you into it. One should never take risks (because one knows there is protection there) that one wouldn't take without it. I disagree that the knowledge that there is an RCCB in the circuit will make me complacent. > I'd rather just work carefully, knowing any mistake I make could be > fatal. I'd rather work carefully, knowing that any mistake I make could be fatal, but also knowing that I have taken all reasonable steps to ensure that it won't. Our protection specialist at Power Tech often talks about prortection in terms of "the fence at the top of the cliff" and "the ambulance at the bottom of the cliff". When working with live high voltages, one should always try and put in place as many "fence" systems as possible - rubber gloves, isolating transformers, insulated screwdrivers, hands in pockets etc., but "ambulance" systems such as residual current devices have their place. Philip.

27 years, 7 months

V35-RS232 cable?

by rcini＠msn.com

Hello, all: One of my recent acquisitions is a Roytron paper tape punch/reader. Before I actually got it, it had a v.35-to-DB25 cable on it . Now it doesn't, of course. I'm ignorant (about many things, but particularly) about v.35, so could this have been an RS-232 adapter cable? If so, how could I make one? Thanks for any info. [ Rich Cini/WUGNET [ ClubWin!/CW7 [ MCP Windows 95/Windows Networking [ Collector of "classic" computers [ http://highgate.comm.sfu.ca/~rcini/classiccmp/ [ http://highgate.comm.sfu.ca/~rcini/pdp11/ <================ reply separator =================>

27 years, 7 months

Amiga 1000 WCS

by mark_k＠iname.com

Hi, I thought I would type up a few paragraphs from "The Amiga System Programmer's Guide" published by Abacus, ISBN 1-55755-034-4 which relate to this. Amiga 1000 WOM -------------- The Amiga 1000 models have additional special features. Owners of these machines may be surprised that we keep talking about a Kickstart ROM, even though the Amiga 1000 loads the Kickstart from disk when it's turned on. The situation with the Amiga 1000 was the following: The hardware was done, the machines were ready to be sold, but the software in the form of the Kickstart operating system wasn't complete and still had some bugs in it. A decision was made to provide the Amiga with special RAM which would be loaded with the operating system when the computer was turned on. After this, the Amiga would prevent write accesses to this RAM, making it behave like a 256K ROM. Commodore called the WOM, or Write-Once Memory. Now the first Amigas could be delivered with the incomplete Kickstart 1.0. After the new Kickstart versions were complete (1.1 and 1.2), the Amiga owner simply had to insert new Kickstart disks. Since this WOM is naturally more expensive than a simple ROM, the Amiga 500 and 2000 are not equipped with it, since by then the final Kickstart (V1.2) was finished. The WOM raises some questions, however: Where is the program which loads Kickstart? How can Kickstart be changed, since it is RAM? Normally the Amiga 1000 operates just like the newer models, with Kickstart at $FC0000 to $FFFFFF with a mirror at $F80000. If you try to write into Kickstart, nothing happens. Write access is not possible. The boot ROM which loads Kickstart is also nowhere to be found in memory. The whole process is controlled by the reset line. After a reset, whether by turning the computer on, by pressing the Amiga, Commodore and Control keys or by executing a 68000 reset command, the memory configuration changes. Reset ----- Immediately after a reset, the boot ROM is at $F80000 (since on a reset the OVL line is set, the reset vector also comes from the boot ROM) and it is possible to write into Kickstart. It can be changed as desired! This condition holds only until you try to write something in the boot ROM range from $F80000 to $FBFFFF. Then the boot ROM is masked out again and the Kickstart memory is write-protected. In short: Reset keeps the Kickstart WOM in memory and enables the boot ROM. A write access to an address between $F80000 and $FBFFFF disables the write protection and the boot ROM. [This should read "enables the write protection and disables the boot ROM."] -- Mark

27 years, 7 months

NEC APCIII

by lfb107＠psu.edu

I had similar problems with my pair of APCIII's. Frustrated, and in need of extra space, I threw them out, but I managed to save most anything that wasn't permanently attached to the case. I've got a few of the memory boards that slid in the back as well as a few parallel cards I think. I also (think) that I have a few of those NLE cards that plugged in the front. The two that i had also had another smaller (memory?) card that plugged in to a special slot at the front, an external HD connector (and a HD.... SCSI?), and a special keyboard with special buttons for graphic functions. Not surprising since they booted up with the DOS 2.11 version of AutoCAD. I couldn't, for the life of me, get them to run anything else! If anyone needs any parts let me know, I haven't got much use for them. Les lfb107(a)psu.edu

27 years, 7 months

New subscriber found TI Explorer, Rainbow 100, and Pro380

by mmcfadden＠cmh.edu

I'm a new guy on this list from Kansas City. My biggest problem is my house doesn't have a basement or a garage, I keep my computer toys in the rec room under the Ping-Pong table. When the garage is built I'll have a computer spot for more stuff. I've been lurking in this group for awhile. I'm from the cardpunching/papertape reading generation of PDP8 and PDP11 types. Pre RSX-11M and RT-11. I wander into a not-for-profit computer surplus place every week. Recently I investigated the salvage room in the basement, they have lots of non PC and non Mac stuff there. Here is what I found I'm looking for more information about them. TI Explorer VME tower style machine external case dual full height 5 1/4 hard drives external case tape backup unit Might be a LISP machine TI doesn't seem to have and information about this machine on their web site. I found Usenet group ti.explorer with not much traffic. Rainbow 100 special DEC floppy DEC Pro 380 special DEC floppy and ST251 hard drive DEC PDP micro 11/23 in tower case Maybe I'll crosspost to alt.computers.pdp11. Glad to be aboard! mmcfadden(a)cmh.edu Real computer can run for months without crashing, all other kinds are only wannabe's.

27 years, 7 months

Require Transputer software & documentation

by rmeenaks＠olf.com

Hi, I maintain the transputer homepage at http://www.geocities.com/SiliconValley/Heights/1190 and I am looking for transputer software & documentation to add to my webpage. If anyone is willing to part with their transputer trams, boards, etc. Let me know, I will gladly take it from you. Ram

27 years, 7 months

HP 2000 Time Shared BASIC Memories

by fmc＠reanimators.org

"Jay West" <jlwest(a)tseinc.com> wrote: > Yes, there is an emulator for the 2100 series cpu. Check out Jeff Moffat's > website. Don't remember the URL, but search yahoo & such for "2100" and > you'll find it. He has an emulator that runs on dos. It is supposed to run > on Unix, but - it has some real problems with FreeBSD. Another user on the > list here was kind enough to fix it up for freebsd and send me a diff file. It's OK to blame me in public, Jay. I probably still have the diffs around too. The diffs pretty much just make bugs come out elsewhere (to wit, instead of the simulator's text being emitted with LF-only newlines so they're hard to read, the simulator aborts when the simulated 2100 halts), and I really ought to quit screwing around with e-mail and spend the time working on fixing the problem by making the controlling terminal abstraction a little bit more abstract and probably cleaning up the Un*x terminal I/O code some too; it's lifted from Doug Jones' PDP-8 simulator and it does some non-POSIXy things. OTOH if I make it POSIXy it will probably not work on older Un*xes. Decisions, decisions. Jeff Moffatt and I did exchange e-mail about it two or three weeks ago and then I got sidetracked by the day job. Turns out he did most of his development and testing under MS-DOS. -Frank McConnell

27 years, 7 months

Need data sheet for 1101 RAM, 8008

by ddameron＠earthlink.net

Hi Sam and all, At 01:30 PM 2/24/99 -0800, you wrote: > >Does anyone have the data sheets for the 1101 RAM and the Intel 8008? I >need both. In the case of the 8008, an instruction set listing would also >be cool. I have both the AMD and Intel data sheets for the 1101(A). They also may be in a early (~1976) Intel data catalog. For the 8008, the best is the mcs8 microcomputer set users manual. Someone on the list just found one in the last week or 2. I probably have a "condensed" data sheet from a Intel catalog as well. The mcs8 book is about 100 pages. The instruction set would be only 4 pages or so. I might have some data >from the Canadian company that second sourced the 8008?? > >Anyone know where 1101 RAM chips are for sale (if at all?) A few years ago I searched all over the place, not only Halted, James, ACP, and any other advertisers in early Byte magagines that might still exist, but the "obsolete ic" house resellers too. Remember the ads for "8008 +8 2102's"? I only found about 3 "tubes", but may not ever use them as wire wrapping 8 chips give only 256 bytes. How many do you want? Can't you find this stuff by the barrel and data sheets by the ream there in Si valley :-)? ..Like a west coast "Poly Pac's". No I don't expect to find a Mark 8 or Scelbi, so am moving slowly to building a 8008 system. I did finally find a copy of "Microcomputer Design" by Martin by interlibrary loan :). Abebooks, etc never found it. It is loaded with 8008 stuff with things like all timing, a 9 chip 8008 system, etc. They also sold the "Mike" series of microcomputer boards, but I have never seen one except pictures in early Byte's. I also tried to find Martin or his company (In Illinois), but no luck. By the way, searching, I found a rumor that Intel was going to come out with a support chip for all the control logic for the 8008. I have seen no indication they did, just went on to the 8080. > >Sellam Alternate e-mail: dastar(a)siconic.com >--------------------------------------------------------------------------- --- >Always hasslin' the man. > -Dave

27 years, 7 months

Computers on AM Radio...

by cswiger＠wilma.widomaker.com

>Has anyone had their computer "speak" over the radio before? I have a >local (small-town) live radio talk show on one of the local AM stations Dunno about AM but Harry Shearer http://www.harryshearer.com (voice of Mr. Burns et al) does an ocassional sketch with "Ralph the Talking Computer" on his Public Radio FM shows in Santa Monica - of which there is a great online collection at above url. Plug Plug Chuck cswiger(a)widomaker.com

27 years, 7 months

V35-RS232 cable?

by edick＠idcomm.com

I remember at least one contact with this sort of cabling arrangement. The v.35 normally uses a distinctive rectangular connector while most manufacturers like the cheaper 'D' connectors. The use of the 'D' connector has more to do with cable-assembly cost than anything else, and it may not be assumed that there is any implication of signal compatibility. If you intend to play with the v.35, you may want to look at the standard before risking the health of your interface hardware. I haven't looked at it in years, but IIRC, it's a differential arrangement at ECL levels or something on that order. I say this because I seem to have seen ECL logic used to generate the levels in at least one piece of equipment. I don't much regret that I don't remember the details. Now that amateur ISP's are running high-speed telecom interfaces, e.g. DS-3, from their basements, we'll undoubtedly see this one more often. Dick ---------- > From: Bruce Lane <kyrrin(a)bluefeathertech.com> > To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> > Subject: Re: V35-RS232 cable? > Date: Friday, February 26, 1999 7:28 AM > > At 20:33 25-02-1999 -0500, you wrote: > > >Hello, all: > > > > One of my recent acquisitions is a Roytron paper tape punch/reader. > >Before I actually got it, it had a v.35-to-DB25 cable on it . Now it > >doesn't, of course. > > > > I'm ignorant (about many things, but particularly) about v.35, so could > >this have been an RS-232 adapter cable? If so, how could I make one? > > It's not just a simple cable in a case like that. There would also be some > level-shifting electronics involved for at least the data leads because > V.35 is a differential interface. > > I'm a little surprised to hear of a V.35 cable on something like a paper > tape handler. Are you sure the thing really does have a V.35 interface, and > that Roytron didn't just happen to use the same connector that V.35 devices > do? > > > -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > Bruce Lane, Owner and head honcho, Blue Feather Technologies > http://www.bluefeathertech.com > Amateur Radio:(WD6EOS) E-mail: kyrrin(a)bluefeathertech.com > SysOp: The Dragon's Cave (Fido 1:343/272, 253-639-9905) > "Our science can only describe an object, event, or living thing in our own > human terms. It cannot, in any way, define any of them..."

27 years, 7 months

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